Global River Ice Dataset - validation dataset

<strong>Documentation for nws_breakup_nogeo.csv and nws_freezeup_nogeo.csv</strong> Alaskan river ice records from National Weather Service (NWS), including <strong>nws_breakup_nogeo.csv</strong> containing location (description) and dates of ice breakup and related conditions and <strong>nws_freezeup_nogeo.csv </strong>containing location (description) and dates of ice freeze-up and related conditions. Note that both dataset do not contain exact geolocations of the observation. We thank Dr. Scott Lindsey at the Alaska-Pacific River Forecast Center for providing these datasets. <strong>Documentation for landsat_river_ice_validation.csv</strong> This file contains 20,687 same-day river ice condition from Landsat and from in situ, and consists of the following associated properties for each comparison: date: The date on which both the Landsat river ice (length) fraction and in situ river ice condition were observed (data type: string; format: "YYYY-MM-DD"). ice_in_situ: The ice condition on rivers observed in situ. For records from NWS, we assumed river has been ice covered between the date of "first_ice" to the date of "breakup" in the following year and ice-free between the date of "breakup" and the following "first_ice" date. For records from Water Survey of Canada, river was treated as ice-covered whenever the daily "Flow" data were flagged with "B"–meaning backwater effect (data type: integer; range: 0 (ice-free) or 1 (ice-covered)). ice_landsat: The river ice length fraction derived from Landsat image (data type: float; range: [0, 1]). cloud_landsat: The cloud fraction derived from Landsat image (data type: float; range: [0, 0.25]). LANDSAT_SCENE_ID: The unique Landsat TOA image identifier (data type: string). site_id: The ID of the site in its original dataset. dat_source: The source of the in situ river ice record (data type: string; values: ("National Weather Service (Alaska)", "Water Survey of Canada"). longitude: The longitude of the site (data type: float, format: decimal degree). latitude: The latitude of the site (data type: float, format: decimal degree). A subset (N = 18,930) of this dataset was used in the evaluation of the river ice classification. This subset was calculated by applying the following two constraints on the full dataset in the <strong>landsat_river_ice_validation.csv</strong>: \(cloud\_landsat ≤ 0.05\) \(site\_id \neq 10BE013\) &amp; \(site\_id \neq 08KE016\) The second constraint exclude two Canadian sites from the evaluation as via manual inspection, we found that the Landsat-derived ice fraction for this two sites came from river reaches that were different from where the in situ records were observed.<strong>nws_breakup_nogeo.csv 及 nws_freezeup_nogeo.csv 数据集说明文档</strong> 本数据集为源自美国国家气象局（National Weather Service, NWS）的阿拉斯加河流冰情记录，其中<strong>nws_breakup_nogeo.csv</strong>包含观测地点（文字描述）、河流冰融日期及相关冰情信息，<strong>nws_freezeup_nogeo.csv</strong>则包含观测地点（文字描述）、河流封冻日期及相关冰情信息。需注意，两份数据集均未包含观测点的精确地理坐标。特此感谢阿拉斯加-太平洋河流预报中心的斯科特·林赛博士（Scott Lindsey）提供本数据集。 <strong>landsat_river_ice_validation.csv 数据集说明文档</strong> 本数据集包含20687组同日获取的Landsat卫星遥感冰情与原位冰情观测数据，每条对比样本均包含以下关联属性： date：同时获取Landsat河流冰盖长度占比与原位冰情观测的日期（数据类型：字符串；格式为「YYYY-MM-DD」）。 ice_in_situ：原位观测得到的河流冰情。针对美国国家气象局（NWS）的观测记录，我们约定：河流封冻时段为「首次结冰日」至次年「冰融日」，冰融时段为「冰融日」至次年「首次结冰日」；针对加拿大水文调查局（Water Survey of Canada）的观测记录，当每日「流量」字段被标记为「B」（代表存在回水影响）时，判定河流处于封冻状态。该字段数据类型为整数，取值范围为0（无冰覆盖）或1（有冰覆盖）。 ice_landsat：由Landsat影像反演得到的河流冰盖长度占比（数据类型：浮点型；取值范围为[0, 1]）。 cloud_landsat：由Landsat影像计算得到的云量占比（数据类型：浮点型；取值范围为[0, 0.25]）。 LANDSAT_SCENE_ID：Landsat顶层大气（Top of Atmosphere, TOA）影像的唯一标识符（数据类型：字符串）。 site_id：观测站点在原始数据集中的编号（数据类型：字符串）。 dat_source：原位冰情观测记录的来源（数据类型：字符串；可选值为「美国国家气象局（阿拉斯加）」、「加拿大水文调查局」）。 longitude：观测站点的经度（数据类型：浮点型；格式为十进制度数）。 latitude：观测站点的纬度（数据类型：浮点型；格式为十进制度数）。 本数据集的一个子集（样本量N=18930）被用于河流冰情分类模型的性能评估。该子集通过对<strong>landsat_river_ice_validation.csv</strong>全量数据集施加以下两项约束得到： (cloud\_landsat ≤ 0.05) (site\_id eq 10BE013) 且 (site\_id eq 08KE016) 第二项约束将两个加拿大观测站点排除在评估之外，原因是经人工核查发现，这两个站点对应的Landsat反演冰盖占比数据，其对应河段与原位观测记录的河段并不一致。